Mustăţa, Costică. “ Selections With Values Bernstein Polynomials Associated to the Extension Operator for Lipschitz Functions”. Rev. Anal. Numér. Théor. Approx., vol. 22, no. 2, Aug. 1993, pp. 207-16, https://www.ictp.acad.ro/jnaat/journal/article/view/1993-vol22-no2-art11.